This application is a continuation in-part of co-pending U.S. patent application Ser. No. 7/027,292 filed Mar. 17, 1987, now abandoned, the content of which is incorporated herein by reference. The present invention relates to vehicle navigation systems.
Map reading is a skilled task and may cause particular problems in cities where the large number of road intersections and density of traffic can easily give rise to confusion. The problem is compounded when in the absence of a passenger, the driver is forced to do his own map reading and navigation.
The following patents and publications have been cited in the course of prosecution of patent or analog applications to the present application.
______________________________________ UK 2121176A 12/14/83 UK 2020019A 11/07/79 UK 2060880A 05/07/81 EP 0158214 10/16/85 EP 0110171 06/13/84 (French) PCT 84/01823 05/10/84 (German) US 4,688,176 08/87 Hirata US 4,672,563 06/87 Haramatsu US 4,633,709 01/87 Numata JP 61-17911 01/87 Tamura (Japanese) EP 0080736 06/83 (Japan) UK 2180066A 03/18/87 (Foreign Analog of present application) ______________________________________
Of the above patents and publications Hirate is representative of a typical two-dimensional navigation system. Location within an area is determined continuously in two spatial dimensions with reference to an absolute reference such as magnetic north.
The Tamara reference is a still further example of a mechanism requiring continuous detection of orientation. Tamura provides for correction of deviation between a "present position" and a "display position" continually and in at least two dimensions with reference to a coordinate system using a direction sensor, an angle sensor, and an azimuth sensor. Other sensors are also provided.
The UK published application No. 218077A published 3/18/87 is not a reference against the present application as it was published less than one year prior to the effective filing date of the present application. The present application describes enhancements of the previously-described system.